https://www.publishersweekly.com/978-0-06-019413-0
I agree with this summary from the linked:
Unfortunately, for all the book's breadth, Watson's workmanlike approach has the feel of a handful of school assignments cobbled together from encyclopedia articles rather than of work drawn from years of thoughtful reflection and an intimate acquaintance with, and love of, ideas. (Mar. 9)
It is a book best thought of as a shallow encyclopedia that you could look into to find a tiny snippet of the thoughts of MANY thinkers of the 20th century. As I got to towards the end and ran into thinkers that I was familiar with like Alan Bloom "The Closing Of the American Mind", I was struck with an old thought that I once had on "Consumer Reports" which I used to look at with relish. I realized that if I knew about something ... say cars, stereo, or computers, I TOTALLY disagreed with Consumer Reports!
Why? Because CR was targeted at some "hypothetical average" ... NOT at the person who paid attention to the specifics of some product area.
"Modern Mind" is kind of the same in that it assumes the standard of "science is the answer to life, the universe, and everything", "all is stuff (material)", religion is bunk, there is no such thing as "meaning, purpose, morality, etc" ... It does recognize that a most thinkers in the 20th century arrived at the conclusion that all that is true and that fact is damned depressing!
On page 772, it says "Evolution is the story of us all. Physics, chemistry, and biology are international in a way that literature, art, or religion can never be".
Human mind blindness is the only true universal -- belief in evolution is not falsifiable, and therefore a religion, not science. Science can tell you how to build a nuke or a virus that kills all life -- it has nothing to say on if you "should". There is no should in science.
So, the book is a reference to lots of "thought stuff", with a surprising amount of attention paid to art, poetry, and literature ... especially given it's conclusion that we just need to realize that we, and everything that "is", is just meaningless stuff.